Mono-energetic neutral beam activated chemical processing system and method of using

ABSTRACT

A chemical processing system and a method of using the chemical processing system to treat a substrate with a mono-energetic space-charge neutralized neutral beam-activated chemical process is described. The chemical processing system comprises a first plasma chamber for forming a first plasma at a first plasma potential, and a second plasma chamber for forming a second plasma at a second plasma potential greater than the first plasma potential, wherein the second plasma is formed using electron flux from the first plasma. Further, the chemical processing system comprises a substrate holder configured to position a substrate in the second plasma chamber.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method and system for treating a substrateand, more particularly, to a method and system for performing neutralbeam activated chemical processing of a substrate.

2. Description of Related Art

During semiconductor processing, plasma is often utilized to assist etchprocesses by facilitating the anisotropic removal of material along finelines or within vias (or contacts) patterned on a semiconductorsubstrate. Examples of such plasma assisted etching include reactive ionetching (RIE), which is in essence an ion activated chemical etchingprocess.

However, although RIE has been in use for decades, its maturity isaccompanied by several issues including: (a) broad ion energydistribution (IED), (b) various charging-induced side effects; and (c)feature-shape loading effects (i.e., micro loading). One approach toalleviate these problems is to utilize neutral beam processing.

A true neutral beam process takes place essentially without any neutralthermal species participating as the chemical reactant, additive, and/oretchant. The chemical process, such as an etching process, at thesubstrate is activated by the kinetic energy of the incident(directionally energetic) neutral species and the incident(directionally energetic and reactive) neutral species also serve as thereactants or etchants.

One natural consequence of neutral beam processing is the absence ofmicro loading since the process does not involve the effect offlux-angle variation associated with the thermal species (which serve asthe etchants in RIE). However, an adverse consequence of the lack ofmicro loading is the achievement of an etch efficiency of unity, i.e.,the maximum etching yield is unity, or one incident neutral nominallyprompts only one etching reaction. Conversely, the abundant thermalneutral species (the etchant) in RIE can all participate in the etchingof the film, with the activation by one energetic incident ion. Kineticenergy activated (thermal neutral species) chemical etching cantherefore achieve an etch efficiency of 10, 100 and even 1000, whilebeing forced to live with micro loading.

While many attempts have been made to cure these shortcomings, i.e.,etch efficiency, micro loading, charge damage, etc., they still remainand the etch community continues to explore novel, practical solutionsto this problem.

SUMMARY OF THE INVENTION

The invention relates to a method and system for treating a substrateand, more particularly, to a method and system for performing neutralbeam activated chemical processing of a substrate.

Furthermore, the invention relates to a chemical processing system andmethod for treating a substrate with a space-charge neutralized neutralbeam activated chemical process. The chemical processing systemcomprises a first plasma chamber for forming a first plasma at a firstplasma potential, and a second plasma chamber for forming a secondplasma at a second plasma potential greater than the first plasmapotential, wherein the second plasma is formed using electron flux fromthe first plasma. Further, the chemical processing system comprises asubstrate holder configured to position a substrate in the second plasmachamber.

According to one embodiment, a chemical processing system configured totreat a substrate is described, comprising: a plasma generation chambercomprising a first plasma region configured to receive a first processgas at a first pressure; process chamber comprising a second plasmaregion disposed downstream of the first plasma region and configured toreceive the first process gas from the first plasma region at a secondpressure; a first gas injection system coupled to the plasma generationchamber and configured to introduce the first process gas to the firstplasma region; a plasma generation system coupled to the plasmageneration chamber and configured to generate a first plasma at a firstplasma potential in the first plasma region from the first process gas;a separation member disposed between the first plasma region and thesecond plasma region, wherein the separation member comprises one ormore openings configured to allow an electron flux from the first plasmaregion to the second plasma region to form a second plasma at a secondplasma potential; a bias electrode system coupled to the process chamberand configured to elevate the second plasma potential above the firstplasma potential in order to control the electron flux; a substrateholder coupled to the process chamber and configured to support thesubstrate proximate the second plasma region; and a vacuum pumpingsystem coupled to the process chamber and configured to pump the secondplasma region in the process chamber.

According to another embodiment, a method for treating a substrate isdescribed, comprising: disposing the substrate in a process chamberconfigured to treat the substrate; forming a first plasma in a firstplasma region at a first plasma potential; forming a second plasma in asecond plasma region at a second plasma potential using electron fluxfrom the first plasma region; elevating the second plasma potentialabove the first plasma potential to control the electron flux;controlling a pressure in the process chamber; and exposing thesubstrate to the second plasma.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1A shows a chemical processing system according to an embodiment;

FIG. 1B illustrates conditions for a chemical process to be performed inthe chemical processing system depicted in FIG. 1A;

FIG. 2 shows a chemical processing system according to an embodiment;

FIG. 3 shows a chemical processing system according to anotherembodiment;

FIG. 4 shows a chemical processing system according to anotherembodiment; and

FIG. 5 illustrates a method of operating a plasma processing systemconfigured to treat a substrate according to another embodiment.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In the following description, to facilitate a thorough understanding ofthe invention and for purposes of explanation and not limitation,specific details are set forth, such as a particular geometry of theplasma processing system and various descriptions of the systemcomponents. However, it should be understood that the invention may bepracticed with other embodiments that depart from these specificdetails.

Nonetheless, it should be appreciated that, contained within thedescription are features which, notwithstanding the inventive nature ofthe general concepts being explained, are also of an inventive nature.

According to one embodiment, a method and system for performing neutralbeam activated chemical processing of a substrate is provided, interalia, to alleviate some or all of the above identified issues. Neutralbeam activated chemical processing includes kinetic energy activation(i.e., thermal neutral species) and, hence, it achieves high reactive oretch efficiency. However, neutral beam activated chemical processing, asprovided herein, also achieves mono-energetic activation, space-chargeneutrality, and hardware practicality.

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, FIGS. 1Aand 1B depict simplified schematics of a chemical processing systemaccording to an embodiment. As shown in FIG. 1A, a chemical processingsystem 1 is described that is configured to perform space-chargeneutralized neutral beam activated chemical processing of a substrate.

As illustrated in FIGS. 1A and 1B, the chemical processing system 1comprises a first plasma chamber 10 for forming a first plasma 12 at afirst plasma potential (V_(p,1)), and a second plasma chamber 20 forforming a second plasma 22 at a second plasma potential (V_(p,2))greater than the first plasma potential. The first plasma 12 is formedby coupling power, such as radio frequency (RF) power, to an ionizablegas in the first plasma chamber 10, while the second plasma 22 is formedusing electron flux (e.g., energetic electron (ee) current, j_(ee)) fromthe first plasma 12. Further, the chemical processing system 1 comprisesa substrate holder configured to position a substrate 25 at directcurrent (DC) ground or floating ground in the second plasma chamber 20to be exposed to the second plasma 22 at the second plasma potential.

The first plasma chamber 10 comprises a plasma generation system 16configured to ignite and heat the first plasma 12. The first plasma 12may be heated by any conventional plasma generation system including,but not limited to, an inductively coupled plasma (ICP) source, atransformer coupled plasma (TCP) source, a capacitively coupled plasma(CCP) source, an electron cyclotron resonance (ECR) source, a heliconwave source, a surface wave plasma source, a surface wave plasma sourcehaving a slotted plane antenna, etc. Although the first plasma 12 may beheated by any plasma source, it is desired that the first plasma 12 isheated by a method that produces a reduced or minimum fluctuation in itsplasma potential V_(p,1). For example, an ICP source is a practicaltechnique that produces a reduced or minimum V_(p,1) fluctuation.

Additionally, the first plasma chamber 10 comprises a direct current(DC) conductive electrode 14 having a conductive surface that acts as aboundary in contact with the first plasma 12. The DC conductive groundelectrode 14 is coupled to DC ground. The DC conductive ground electrode14 acts as an ion sink that is driven by the first plasma 12 at thefirst plasma potential (V_(p,1)). Although one DC conductive groundelectrode 14 is shown in FIG. 1A, the chemical processing system 1 maycomprise one or more DC conductive ground electrodes.

Although not necessary, it is desirable that the DC conductive groundelectrode 14 comprises a relatively large area in contact with the firstplasma 12. The larger the area at DC ground, the lower the first plasmapotential. For example, the surface area of the conductive surface forthe DC conductive ground electrode 14 in contact with the first plasma12 may be greater than any other surface area in contact with the firstplasma 12. Additionally, for example, the surface area of the conductivesurface for the DC conductive ground electrode 14 in contact with thefirst plasma 12 may be greater than the total sum of all otherconductive surfaces that are in contact with the first plasma 12.Alternatively, as an example, the conductive surface for the DCconductive ground electrode 14 in contact with the first plasma 12 maybe the only conductive surface that is in contact with the first plasma12. The DC conductive ground electrode 12 may offer the lowest impedancepath to ground.

As described above, (energetic) electron flux (or electron currentj_(ee)) from the first plasma 12 initiates and sustains the secondplasma 22 in the second plasma chamber 20. In order to control theelectron flux and produce a mono-energetic space-charge neutralizedneutral beam, the first plasma potential (V_(p,1)), as described above,and the second plasma potential (V_(p,2)) should be stable withsubstantially reduced or minimal fluctuations if any fluctuations atall. To achieve this stability in the second plasma 22, the secondplasma chamber 20 comprises a DC conductive bias electrode 24 having aconductive surface in contact with the second plasma 22, wherein the DCconductive bias electrode 24 is coupled to a DC voltage source 26. TheDC voltage source 26 is configured to bias the DC conductive biaselectrode 24 at a positive DC voltage (+V_(DC)). As a result, the secondplasma potential (V_(p,2)) is a boundary-driven plasma potential drivenby a (+V_(DC)) voltage source, thus causing V_(p,2) to rise to about+V_(DC) and remain substantially stable. Although one DC conductive biaselectrode 24 is shown in FIG. 1A, the chemical processing system 1 maycomprise one or more DC conductive bias electrodes.

Furthermore, the plasma processing system comprises a separation member30 disposed between the first plasma chamber 10 and the second plasmachamber 20. The separation member 30 may act as an electron diffuser.The electron diffusion is driven by an electric field through anelectron acceleration layer created by the potential differenceΔV=V_(p,2)−V_(p,1). The separation member 30 may comprise an insulator,such as quartz or alumina, or the separation member 30 may comprise adielectric coated conductive material that is electrically floating andhas a high RF impedance to ground. Due to the large electric fieldacross the electron acceleration layer (∇_(z)(V_(p,2)-V_(p,1))), theelectron flux is sufficiently energetic to sustain ionization in thesecond plasma 22. However, the chemical processing system 1 mayoptionally comprise a plasma heating system configured to further heatthe second plasma 22.

The separation member 30 may comprise one or more openings to permit thepassage of the energetic electron flux from the first plasma chamber 10to the second plasma chamber 20. The total area of the one or moreopenings can be adjusted relative to the surface area of the DCconductive ground electrode 14 to ensure a relatively large potentialdifference ΔV=V_(p,2)−V_(p,1) while minimizing reverse ion current fromthe second plasma 22 to the first plasma 12, and thereby ensure asufficient ion energy for ions striking the substrate 25.

As illustrated in FIG. 1A, a first ion flux (e.g., ion current, j_(i1))from a first population of ions in the first plasma 12 flows to the DCconductive ground electrode 14 in the first plasma chamber 10 in aquantity approximately equivalent to the energetic electron flux (orelectron current j_(ee)) from the first plasma 12 through the electronacceleration layer at the separation member 30 into the second plasma22, i.e., j_(i1)˜j_(ee).

As described above, the energetic electron flux is sufficientlyenergetic to form the second plasma 22. Therein, a population of thermalelectrons and a second population of ions are formed. The thermalelectrons are largely a result of ejected electrons upon ionization ofthe second plasma 22 by the incoming energetic electron flux (orelectron current j_(ee)). However, some energetic electrons from theenergetic electron flux may lose a sufficient amount of energy and,thus, become part of the thermal electron population.

Due to Debye shielding, only the thermal electrons of the second plasma22 flow to the DC conductive bias electrode 24 (e.g., thermal electroncurrent, j_(te)) in a quantity approximately equal to the energeticelectron flux, i.e., j_(te)˜j_(ee). While thermal electron currentj_(te) is directed to the DC conductive bias electrode 24, a second ionflux from the second population of ions is directed to the substrate atV_(p,2) (as ion current, j_(i2)).

If the incoming energetic electron energy is sufficiently high, asubstantial fraction of the energetic electron flux (j_(ee)) willsurvive the passage through the second plasma 22 and strike wafer 25.However, regardless of their origin (i.e., energetic electrons fromenergetic electron flux j_(ee) or energetic electrons from the thermalelectron population), only energetic electrons capable of passingthrough the substrate sheath (i.e. climbing the potential “hill”) willreach substrate 25. Since substrate 25 is at floating DC ground, the ioncurrent j_(i2) that is fed by the second ion population in the secondplasma 22 will be equivalent to the electron current j_(e2) (i.e., nonet current, or j_(i2)˜j_(e2)). Alternatively, the substrate 25 may beat approximately DC ground since the floating-ground surface potentialis expected to be slightly above DC ground.

In such a configuration for the chemical processing system 1, theelevation of the second plasma potential above the first plasmapotential drives an energetic electron beam (having electron currentj_(ee)) to form the second plasma 22, while particle balance throughoutthe chemical processing system 1 enforces an equal number of electrons(e.g., electron current, j_(e2)) and ions (e.g., ion current, j_(i2))striking substrate 25 (i.e., j_(i2)˜j_(e2)). This charge balancemanifests as a space-charge neutralized neutral beam directed tosubstrate 25 that activates a chemical process at substrate 25.

Referring now to FIG. 2, a chemical processing system 101 is providedaccording to an embodiment. The chemical processing system 101 comprisesa plasma generation chamber 105 configured to produce a first plasma 143at a first plasma potential, and a process chamber 110 configured toprovide a contaminant-free, vacuum environment for plasma processing ofa substrate 125. The process chamber 110 comprises a substrate holder120 configured to support substrate 125, and a vacuum pumping system 130coupled to the process chamber 110 and configured to evacuate theprocess chamber 110 and control a pressure in the process chamber 110.

The plasma generation chamber 105 comprises a first plasma region 142configured to receive a first process gas at a first pressure and formthe first plasma 143. Furthermore, the process chamber 110 comprises asecond plasma region 152 disposed downstream of the first plasma region142 and configured to receive electron flux 150 and the first processgas from the first plasma region 142 and form a second plasma 153therein at a second plasma potential and a second pressure.

A first gas injection system 144 is coupled to the plasma generationchamber 105, and configured to introduce the first process gas to thefirst plasma region 142. The first process gas may comprise anelectropositive gas or an electronegative gas or a mixture thereof. Forexample, the first process gas may comprise a noble gas, such as argon(Ar). Additionally, for example, the first process gas may comprise anygas suitable for treating substrate 125. Furthermore, for example, thefirst process gas may comprise any gas having chemical constituents,atomic or molecular, suitable for treating substrate 125. These chemicalconstituents may comprise etchants, film forming gases, dilutants,cleaning gases, etc. The first gas injection system 144 may include oneor more gas supplies or gas sources, one or more control valves, one ormore filters, one or more mass flow controllers, etc.

An optional second gas injection system 154 may be coupled to theprocess chamber 110, and configured to introduce a second process gas tothe second plasma region 152. The second process gas may comprise anygas suitable for treating substrate 125. Additionally, for example, thesecond process gas may comprise any gas having chemical constituents,atomic or molecular, suitable for treating substrate 125. These chemicalconstituents may comprise etchants, film forming gases, dilutants,cleaning gases, etc. The second gas injection system may include one ormore gas supplies or gas sources, one or more control valves, one ormore filters, one or more mass flow controllers, etc.

Referring still to FIG. 2, the chemical processing system 101 comprisesa plasma generation system 140 coupled to the plasma generation chamber105 and configured to generate the first plasma 143 in the first plasmaregion 142. The plasma generation system 140 can comprise a systemconfigured to produce a capacitively coupled plasma (CCP), aninductively coupled plasma (ICP), a transformer coupled plasma (TCP), asurface wave plasma, a helicon wave plasma, or an electron cyclotronresonant (ECR) heated plasma, or other type of plasma understood by oneskilled in the art of plasma formation. Although the first plasma may beheated by any plasma source, it is desired that the first plasma isheated by a method that produces a minimum fluctuation in its plasmapotential V_(p,1). For example, an ICP source is a practical techniquethat produces a reduced or minimum V_(p,1) fluctuation.

As shown in FIG. 2, the plasma generation system 140 may comprise aninductive coil 148 which is coupled to a power source 146. The powersource 146 may comprise a radio frequency (RF) generator that couples RFpower through an optional impedance match network to inductive coil 148.RF power is inductively coupled from inductive coil 148 through adielectric window 108 to the first plasma 143 in the first plasma region142. A typical frequency for the application of RF power to theinductive coil can range from about 10 MHz to about 100 MHz. Inaddition, a slotted Faraday shield (not shown) can be employed to reducecapacitive coupling between the inductive coil 148 and plasma.

An impedance match network may serve to improve the transfer of RF powerto plasma by reducing the reflected power. Match network topologies(e.g. L-type, π-type, T-type, etc.) and automatic control methods arewell known to those skilled in the art.

As an example, in an electropositive discharge, the electron density mayrange from approximately 10¹⁰ cm⁻³ to 10¹³ cm⁻³, and the electrontemperature may range from about 1 eV to about 10 eV (depending on thetype of plasma source utilized).

Additionally, as shown in FIG. 2, the plasma generation chamber 105comprises a direct current (DC) conductive electrode 106 having aconductive surface that acts as a boundary in contact with the firstplasma 143. The DC conductive ground electrode 106 is coupled to DCground. For example, the DC conductive ground electrode 106 may comprisea doped silicon electrode. The DC conductive ground electrode 106 actsas an ion sink that is driven by the first plasma 143 at the firstplasma potential (V_(p,1)). Although one DC conductive ground electrode106 is shown in FIG. 2, the chemical processing system 101 may compriseone or more DC conductive ground electrodes.

Although not necessary, it is desirable that the DC conductive groundelectrode 106 comprises a relatively large area in contact with thefirst plasma 143. The larger the area at DC ground, the lower the firstplasma potential. For example, the surface area of the conductivesurface for the DC conductive ground electrode 106 in contact with thefirst plasma 143 may be greater than any other surface area in contactwith the first plasma 143. Additionally, for example, the surface areaof the conductive surface for the DC conductive ground electrode 106 incontact with the first plasma 143 may be greater than the total sum ofall other conductive surfaces that are in contact with the first plasma143. Alternatively, as an example, the conductive surface for the DCconductive ground electrode 106 in contact with the first plasma 143 maybe the only conductive surface that is in contact with the first plasma143. The DC conductive ground electrode 106 may offer the lowestimpedance path to ground.

Referring still to FIG. 2, the chemical processing system 101 furthercomprises a bias electrode system 180 coupled to the process chamber110. The electrode bias system 180 is configured to elevate the secondplasma potential to a value above the first plasma potential in order todrive the electron flux. The bias electrode system 180 comprises a DCconductive bias electrode 182 having a conductive surface in contactwith the second plasma 153. The DC conductive bias electrode 182 iselectrically insulated from the process chamber 110 via insulator 184and the DC conductive bias electrode 182 is coupled to a DC voltagesource 186. The conductive bias electrode 182 is composed of aconductive material, such as a metal or doped silicon. Although one DCconductive bias electrode 182 is shown in FIG. 2, the chemicalprocessing system 101 may comprise one or more DC conductive biaselectrodes.

Although not necessary, it is desirable that the DC conductive biaselectrode 182 comprises a relatively large area in contact with thesecond plasma 153. The larger the area at +V_(DC), the closer the secondplasma potential will be to +V_(DC). As an example, the total area ofthe DC conductive bias electrode 182 may be greater than the total sumof all other conductive surfaces that are in contact with the secondplasma 153. Alternatively, as an example, the total area of the DCconductive bias electrode 182 may be the only conductive surface that isin contact with the second plasma 153.

The voltage source 186 can include a variable DC power supply.Additionally, the DC voltage source 186 can include a bipolar DC powersupply. The DC voltage source 186 can further include a systemconfigured to perform at least one of monitoring adjusting, orcontrolling the polarity, current, voltage, or on/off state of the DCvoltage source 186. An electrical filter may be utilized to de-couple RFpower from the DC voltage source 186.

For example, the DC voltage applied to the DC conductive bias electrode182 by DC voltage source 186 may range from approximately 0 volts (V) toapproximately 10000 V. Desirably, the DC voltage applied to the DCconductive bias electrode 182 by DC voltage source 186 may range fromapproximately 50 volts (V) to approximately 5000 V. Additionally, it isdesirable that the DC voltage has a positive polarity. Furthermore, itis desirable that the DC voltage is a positive voltage having anabsolute value greater than approximately 50 V.

As shown in FIG. 2, the process chamber 110 comprises a chamber housingmember 111 that may be coupled to ground. Additionally, a liner member188 may be disposed between the chamber housing member 111 and thesecond plasma 153. The liner member 188 may be fabricated from adielectric material, such as quartz or alumina. The liner member 188 mayprovide a high RF impedance to ground for the second plasma 153.Further, an electrical feed-through 187 is configured to allowelectrical connection to the DC conductive bias electrode 182.

Referring still to FIG. 2, a separation member 170 is disposed betweenthe first plasma region 142 and the second plasma region 152, whereinthe separation member 170 comprises one or more openings 172 configuredto allow passage of the first process gas as well as electron flux 150from the first plasma 143 in the first plasma region 142 to the secondplasma region 152 in order to form the second plasma 153 in the secondplasma region 152.

The one or more openings 172 in the separation member 170 may comprisesuper-Debye length apertures, i.e., the transverse dimension or diameteris larger than the Debye length. The one or more openings 172 may besufficiently large to permit adequate electron transport, and the one ormore openings 172 may be sufficiently small to allow a sufficiently highpotential difference between the first plasma potential and the secondplasma potential and to reduce any reverse ion current between thesecond plasma 153 and the first plasma 143. Further, the one or moreopenings 172 may be sufficiently small to sustain a pressure differencebetween the first pressure in the first plasma region 142 and the secondpressure in the second plasma region 152.

Although the DC conductive ground electrode 106 is coupled to DC ground,it may be coupled to a DC voltage less than the bias DC voltage coupledto the DC conductive bias electrode 182.

As illustrated in FIG. 2, electron flux 150 occurs between the firstplasma region 142 and the second plasma region 152 through separationmember 170. The electron transport is driven by electric field-enhanceddiffusion, wherein the electric field is established by the potentialdifference between the first plasma potential and the second plasmapotential. The electron flux 150 is sufficiently energetic to sustainionization in the second plasma 153.

Vacuum pumping system 130 may, for example, include a turbo-molecularvacuum pump (TMP) capable of a pumping speed up to 5000 liters persecond (and greater) and a vacuum valve (or second vacuum valve), suchas a gate valve, for controlling the pressure in the second plasmaregion 152. Furthermore, a device for monitoring chamber pressure (notshown) can be coupled to the process chamber 110. The pressure measuringdevice may be, for example, a Type 628B Baratron absolute capacitancemanometer commercially available from MKS Instruments, Inc. (Andover,Mass.).

Referring still to FIG. 2, the substrate holder 120 can be coupled toground. If the substrate holder 120 is coupled to ground, the substrate125 may be at floating ground and, therefore, the only ground the secondplasma 153 contacts is the floating ground provided by substrate 125.For example, when the substrate 125 is clamped to substrate holder 120,a ceramic electrostatic clamp (ESC) layer may insulate the substrate 125from the grounded substrate holder 120.

Alternatively, the chemical processing system 101 may comprise asubstrate bias system coupled to substrate holder 120 and configured toelectrically bias substrate 125. For example, the substrate holder 120may include an electrode that is coupled to a RF generator through anoptional impedance match network. A typical frequency for theapplication of power to the substrate holder 120 may range from about0.1 MHz to about 100 MHz.

Referring still to FIG. 2, chemical processing system 101 may comprise asubstrate temperature control system coupled to the substrate holder 120and configured to adjust and control the temperature of substrate 125.The substrate temperature control system comprises temperature controlelements, such as a cooling system including a re-circulating coolantflow that receives heat from substrate holder 120 and transfers heat toa heat exchanger system (not shown), or when heating, transfers heatfrom the heat exchanger system. Additionally, the temperature controlelements can include heating/cooling elements, such as resistive heatingelements, or thermoelectric heaters/coolers, which can be included inthe substrate holder 120, as well as the chamber wall of the processchamber 110 and any other component within the chemical processingsystem 101.

In order to improve the thermal transfer between substrate 125 andsubstrate holder 120, substrate holder 120 can include a mechanicalclamping system, or an electrical clamping system, such as anelectrostatic clamping (ESC) system, to affix substrate 125 to an uppersurface of substrate holder 120. Furthermore, substrate holder 120 canfurther include a substrate backside gas delivery system configured tointroduce gas to the back-side of substrate 125 in order to improve thegas-gap thermal conductance between substrate 125 and substrate holder120. Such a system can be utilized when temperature control of thesubstrate is required at elevated or reduced temperatures. For example,the substrate backside gas system can comprise a two-zone gasdistribution system, wherein the helium gas gap pressure can beindependently varied between the center and the edge of substrate 125.

As shown in FIG. 2, the substrate holder 120 may be surrounded by abaffle member 121 that extends beyond a peripheral edge of the substrateholder 120. The baffle member 121 may serve to homogeneously distributethe pumping speed delivered by the vacuum pumping system 130 to thesecond plasma region 152. The baffle member 121 may be fabricated from adielectric material, such as quartz, or alumina. The baffle member 121may provide a high RF impedance to ground for the second plasma 153.

Referring still to FIG. 2, chemical processing system 101 can furthercomprise a controller 190. Controller 190 comprises a microprocessor,memory, and a digital I/O port capable of generating control signalssufficient to communicate and activate inputs to chemical processingsystem 101 as well as monitor outputs from chemical processing system101. Moreover, controller 190 can be coupled to and can exchangeinformation with plasma generation system 140 including first gasinjection system 144 and power source 146, electrode bias system 180including optional second gas injection system 154 and DC voltage source186, substrate holder 120, and vacuum pumping system 130. For example, aprogram stored in the memory can be utilized to activate the inputs tothe aforementioned components of chemical processing system 101according to a process recipe in order to perform the method of treatingsubstrate 125.

However, the controller 190 may be implemented as a general purposecomputer system that performs a portion or all of the microprocessorbased processing steps of the invention in response to a processorexecuting one or more sequences of one or more instructions contained ina memory. Such instructions may be read into the controller memory fromanother computer readable medium, such as a hard disk or a removablemedia drive. One or more processors in a multi-processing arrangementmay also be employed as the controller microprocessor to execute thesequences of instructions contained in main memory. In alternativeembodiments, hard-wired circuitry may be used in place of or incombination with software instructions. Thus, embodiments are notlimited to any specific combination of hardware circuitry and software.

The controller 190 includes at least one computer readable medium ormemory, such as the controller memory, for holding instructionsprogrammed according to the teachings of the invention and forcontaining data structures, tables, records, or other data that may benecessary to implement the present invention.

The term “computer readable medium” as used herein refers to any mediumthat participates in providing instructions to the processor of thecontroller 190 for execution. A computer readable medium may take manyforms, including but not limited to, non-volatile media, volatile media,and transmission media. Non-volatile media includes, for example,optical, magnetic disks, and magneto-optical disks, such as the harddisk or the removable media drive. Volatile media includes dynamicmemory, such as the main memory. Moreover, various forms of computerreadable media may be involved in carrying out one or more sequences ofone or more instructions to processor of controller for execution. Forexample, the instructions may initially be carried on a magnetic disk ofa remote computer. The remote computer can load the instructions forimplementing all or a portion of the present invention remotely into adynamic memory and send the instructions over a network to thecontroller 190.

Stored on any one or on a combination of computer readable media, theinvention includes software for controlling the controller 190, fordriving a device or devices for implementing the invention, and/or forenabling the controller to interact with a human user. Such software mayinclude, but is not limited to, device drivers, operating systems,development tools, and applications software. Such computer readablemedia further includes the computer program product of the invention forperforming all or a portion (if processing is distributed) of theprocessing performed in implementing the invention.

The computer code devices may be any interpretable or executable codemechanism, including but not limited to, scripts, interpretableprograms, dynamic link libraries (DLLs), Java classes, and completeexecutable programs. Moreover, parts of the processing may bedistributed for better performance, reliability, and/or cost.

Controller 190 may be locally located relative to the chemicalprocessing system 101, or it may be remotely located relative to thechemical processing system 101 via an internet or intranet. Thus,controller 190 can exchange data with the chemical processing system 101using at least one of a direct connection, an intranet, or the internet.Controller 190 may be coupled to an intranet at a customer site (i.e., adevice maker, etc.), or coupled to an intranet at a vendor site (i.e.,an equipment manufacturer). Furthermore, another computer (i.e.,controller, server, etc.) can access controller 190 to exchange data viaat least one of a direct connection, an intranet, or the internet.

Referring now to FIG. 3, a chemical processing system 101′ is providedaccording to another embodiment. The chemical processing system 101′comprises like components as in the chemical processing system 101depicted in FIG. 2. However, chemical processing system 101′ comprises aplasma generation system 140′ having an inductive coil 148′ locatedabove the plasma generation chamber 105. The inductive coil 148′ may bea planar coil, such as a “spiral” coil or “pancake” coil, incommunication with the plasma from above as in a transformer coupledplasma (TCP). RF power is inductively coupled from inductive coil 148′through a dielectric window 108′ to the first plasma 143 in the firstplasma region 142. The design and implementation of an ICP source, orTCP source, is well known to those skilled in the art.

Additionally, as shown in FIG. 3, the plasma generation chamber 105comprises a direct current (DC) conductive ground electrode 106′ havinga conductive surface that acts as a boundary in contact with the firstplasma 143. The at least one DC conductive ground electrode 106′ iscoupled to DC ground.

Referring now to FIG. 4, a chemical processing system 101″ is providedaccording to another embodiment. The chemical processing system 101″comprises like components as in the chemical processing system 101depicted in FIG. 2. However, chemical processing system 101″ comprises aplasma generation system 140″ having an inductive coil 148″ locatedwithin the first plasma region 142 of the plasma generation chamber 105,wherein the inductive coil 148″ is separated from the first plasma 143by a cylindrical dielectric window insert 108″. The inductive coil 148″may be a cylindrical coil, such as a helical coil, that is coupled topower source 146. RF power may be inductively coupled from inductivecoil 148″ through the cylindrical dielectric window insert 108″ to thefirst plasma 143 in the first plasma region 142. The design andimplementation of an ICP source is well known to those skilled in theart.

Additionally, as shown in FIG. 4, the plasma generation chamber 105comprises a direct current (DC) conductive ground electrode 106″ havinga conductive surface that acts as a boundary in contact with the firstplasma 143. The DC conductive ground electrode 106″ is coupled to DCground. As shown in FIG. 4, since the inductive coil 148″ is immersedwithin the first plasma 143, the DC conductive ground electrode 106″comprises a surface area that occupies a substantial fraction of theinterior surfaces of the plasma generation chamber 105.

Referring now to FIG. 5, a flow chart 400 is provided of a method foroperating a plasma processing system to treat a substrate according toan embodiment of the invention. Flow chart 400 begins in 410 withdisposing a substrate in a plasma processing system configured tofacilitate the treatment of the substrate using plasma. The plasmaprocessing chamber may include components of any one of the plasmaprocessing systems described in FIGS. 1A, 1B, 2, 3 and 4.

In 420, a first plasma is formed from a first process gas in a firstplasma region at a first plasma potential. As illustrated in FIGS. 1A,1B, 2, 3 and 4, the first plasma region may be located in a plasmageneration chamber, and a plasma generation system may be coupled to theplasma generation chamber in order to form the first plasma.

In 430, a second plasma is formed in a second plasma region at a secondplasma potential using electron flux from the first plasma. Electronflux from the first plasma in the first plasma region passes from theplasma generation chamber through a separation member to a processchamber where the substrate is to be treated. As illustrated in FIGS.1A, 1B, 2, 3 and 4, the second plasma region may be located in a processchamber, wherein one or more openings or passages in the separationmember disposed between the plasma generation chamber and the processchamber facilitate the transport or supply of electrons from the firstplasma region to the second plasma region.

In 440, the second plasma potential is elevated above the first plasmapotential to control the electron flux. The first plasma in the firstplasma region may be a boundary-driven plasma (i.e., the plasma boundaryhas a substantive influence on the respective plasma potential), whereinpart or all of the boundary in contact with the first plasma is coupledto DC ground. Additionally, the second plasma in the second plasmaregion may be a boundary-driven plasma, wherein part or all of theboundary in contact with the second plasma is coupled to a DC voltagesource at +V_(DC). The elevation of the second plasma potential abovethe first plasma potential may be performed using any one or combinationof the embodiments provided in FIGS. 1A, 1B, 2, 3 and 4.

In 450, gases entering the process chamber are pumped by a vacuumpumping system to control a pressure in the process chamber. In 460, thesubstrate is exposed to the second plasma in the second plasma region.The exposure of the substrate to the second plasma may comprise exposingthe substrate to a mono-energetic space-charge neutralized neutral beamactivated chemical process.

Although only certain embodiments of this invention have been describedin detail above, those skilled in the art will readily appreciate thatmany modifications are possible in the embodiments without materiallydeparting from the novel teachings and advantages of this invention.Accordingly, all such modifications are intended to be included withinthe scope of this invention.

1. A chemical processing system configured to treat a substrate,comprising: a plasma generation chamber comprising a first plasma regionconfigured to receive a first process gas at a first pressure; a processchamber comprising a second plasma region disposed downstream of saidfirst plasma region and configured to receive said first process gasfrom said first plasma region at a second pressure; a first gasinjection system coupled to said plasma generation chamber andconfigured to introduce said first process gas to said first plasmaregion; a plasma generation system coupled to said plasma generationchamber and configured to generate a first plasma at a first plasmapotential in said first plasma region from said first process gas; aseparation member disposed between said first plasma region and saidsecond plasma region, wherein said separation member comprises one ormore openings configured to allow an electron flux from said firstplasma region to said second plasma region to form a second plasma at asecond plasma potential; a bias electrode system coupled to said processchamber and configured to elevate said second plasma potential abovesaid first plasma potential in order to control said electron flux; asubstrate holder coupled to said process chamber and configured tosupport said substrate proximate said second plasma region; and a vacuumpumping system coupled to said process chamber and configured to pumpsaid second plasma region in said process chamber.
 2. The chemicalprocessing system of claim 1, further comprising: a second gas injectionsystem coupled to said process chamber and configured to introduce asecond process gas to said second plasma region.
 3. The chemicalprocessing system of claim 1, wherein said plasma generation systemcomprises an inductive coil configured to inductively couple power froma power source to said first process gas in said first plasma region. 4.The chemical processing system of claim 1, wherein said plasmageneration system comprises a capacitively coupled plasma (CCP) source,an inductively coupled plasma (ICP) source, a transformer coupled plasma(TCP) source, a surface wave plasma source, a helicon wave plasmasource, or an electron cyclotron resonance (ECR) plasma source, or acombination of two or more thereof.
 5. The chemical processing system ofclaim 1, wherein said plasma generation chamber comprises at least onedirect current (DC) conductive ground electrode having a conductivesurface in contact with said first plasma, and wherein said at least oneDC conductive ground electrode is coupled to DC ground.
 6. The chemicalprocessing system of claim 5, wherein said at least one DC conductiveground electrode comprises a doped silicon electrode.
 7. The chemicalprocessing system of claim 5, wherein said conductive surface of said atleast one DC conductive ground electrode comprises a surface area incontact with said first plasma greater than any other surface area incontact with said first plasma.
 8. The chemical processing system ofclaim 1, wherein said separation member is composed of a dielectricmaterial.
 9. The chemical processing system of claim 1, wherein one ormore of said one or more openings in said separation member comprises adiameter greater than or equal to a Debye length.
 10. The chemicalprocessing system of claim 1, wherein said bias electrode systemcomprises at least one DC conductive bias electrode having a conductivesurface in contact with said second plasma, and wherein said at leastone DC conductive bias electrode is coupled to a DC voltage source. 11.The chemical processing system of claim 10, wherein said at least one DCconductive bias electrode comprises a doped silicon electrode.
 12. Thechemical processing system of claim 10, wherein said DC voltage sourceis configured to bias said at least one DC conductive bias electrodewith a DC voltage ranging from about 50 V to about 5000V.
 13. Thechemical processing system of claim 10, wherein said process chambercomprises: a chamber housing member that is fabricated from a DCconductive material and is coupled to DC ground; a liner member coupledto said chamber housing member that is fabricated from a dielectricmaterial and is configured to electrically insulate said chamber housingmember from said second plasma; an electrical feed-through that isconfigured to allow electrical connection to said at least one DCconductive bias electrode; and an electrode insulator disposed betweensaid at least one DC conductive bias electrode and said chamber housingmember and configured to electrically insulate said at least one DCconductive bias electrode from said chamber housing member.
 14. Thechemical processing system of claim 1, wherein said substrate holder iscoupled to DC ground, and wherein said substrate is at DC ground orfloating ground.
 15. The chemical processing system of claim 1, furthercomprising: a controller coupled to said plasma generation system, saidbias electrode system, said process chamber, said first gas injectionsystem, said substrate holder, and said vacuum pumping system, andconfigured to adjust or control said second plasma by varying at leastone of a power coupled by said plasma generation system to said firstprocess gas in said first plasma region, a DC voltage coupled to saidsecond plasma by said bias electrode system, a composition of said firstprocess gas coupled to said plasma generation chamber, a flow rate ofsaid first process gas coupled to said plasma generation chamber, apumping speed coupled to said process chamber, or a temperature of saidsubstrate, or a combination of one or more thereof.
 16. A chemicalprocessing system configured to treat a substrate, comprising: a firstplasma chamber for forming a first plasma at a first plasma potential; asecond plasma chamber for forming a second plasma at a second plasmapotential greater than said first plasma potential, wherein said secondplasma is formed using electron flux from said first plasma; and asubstrate holder configured to position a substrate in said secondplasma chamber.
 17. The chemical processing system of claim 16, whereinsaid first plasma is driven by a first boundary at DC ground voltage,and wherein said second plasma is driven by a second boundary at a DCbias voltage.
 18. The chemical processing system of claim 16, whereinsaid substrate holder is coupled to DC ground, and wherein saidsubstrate is at DC ground or floating ground.
 19. The chemicalprocessing system of claim 16, wherein said first plasma chambercomprises at least one DC conductive ground electrode having aconductive surface in contact with said first plasma, and wherein saidat least one DC conductive ground electrode is coupled to DC ground. 20.The chemical processing system of claim 16, further comprising: aseparation member disposed between said first plasma chamber and saidsecond plasma chamber, wherein said separation member comprises one ormore openings configured to allow said electron flux from said firstplasma to said second plasma, and wherein said separation member iscomposed of a dielectric material.
 21. The chemical processing system ofclaim 16, wherein said second chamber region comprises at least one DCconductive bias electrode having a conductive surface in contact withsaid second plasma, and wherein said at least one DC conductive biaselectrode is coupled to a DC voltage source.
 22. A method for treating asubstrate, comprising: disposing said substrate in a process chamberconfigured to treat said substrate with plasma; forming a first plasmain a first plasma region at a first plasma potential; forming a secondplasma in a second plasma region at a second plasma potential usingelectron flux from said first plasma region; elevating said secondplasma potential above said first plasma potential to control saidelectron flux; controlling a pressure in said process chamber; andexposing said substrate to said second plasma.
 23. The method of claim22, wherein said exposing said substrate to said second plasma comprisesexposing said substrate to a mono-energetic space-charge neutralizedneutral beam activated chemical process.